Use Shrew with Computed Field module in Drupal to store/extract MARC data

gistfile1.php

<?php
/* Sample Computed Field/Shrew usage for Drupal. The Shrew module [1] uses the 
Shrew [2] PHP library to interact with Innovative Interfaces online library
catalog systems. 

[1] http://www.github.com/anarchivist/drupal-shrew
[2] http://www.github.com/anarchivist/shrew
*/

if (!$node->nid) {
node_save($node);
}
$delta = 0;
$node_field = array();
if ($bnum = $node->field_iii_single[0]['value']) {
  $record = shrew_record_get($bnum);
  if ($fields = shrew_field_get($record[$bnum]->bibliographicRecord, '520')) {
    foreach ($fields as $field) {
      $node_field[$delta]['value'] = $field;
      $delta++;
    }
  }
  else $node_field[0]['value'] = NULL;
}